SLC2A1 and lip and oral cavity carcinoma: GLUT1 has been proposed by several authors as an endogenous marker for hypoxia in solid malignancies, including OC.20 In the central parts of lesions with inadequate glucose supply due to increased oxygen diffusion distance, hypoxia-stimulated GLUT1 expression increases to compensate for this condition, causing areas of squamous differentiation and/or keratinization in oral carcinomas.18